Such a multiway valve is known, for example, from DE 198 16 522 A1. This prior-art valve is shown in FIGS. 1 through 4 (FIGS. 1.1 to 4.4) in respect to its general design and its mode of operation and will be described below in reference to these figures.
It is recognized especially from FIGS. 2.1 to 2.4 that this prior-art multiway valve has a valve body, which is generally designated by 2, has a pot-shaped or cylinder-like valve body and in which a valve chamber 8 is formed. Four valve connections 3, 4, 5 and 6 provided in the form of connecting pieces, openings or the like open into the cylindrical circumferential wall of the valve body 2 and are thus, in principle, in connection with the valve chamber 8. It is recognized that the four valve connections 3, 4, 5, 6 are arranged such that they are located opposite each other in pairs, so that the valve connections 3, 4 are located opposite each other in a first plane, which is the upper plane in FIG. 2, with an angular distance of 180° relative to the longitudinal axis of the valve body, while the two valve connections 5 and 6 are located opposite each other with an angular distance of 180° in a second plane, which is the lower plane, and provisions may be made, for example, for the valve connection 5 to be located directly under the valve connection 3 of the other pair of valve connections, while the valve connection 6 is located directly under the valve connection 4 of the other pair of valve connections.
A valve member 1 of an essentially cylindrical or even regular cylindrical design, which is adapted to the contour of the valve body 12, is provided in the valve body 12. This valve member can be driven in the area of a drive shaft 7 by a drive motor, not shown, for rotation around the axis A. Associated with each pair of valve connections 3 and 4 as well as 5 and 6, the valve member 1 has respective openings 10, 11, 12 and 13, 14, 15. These two groups of openings 10, 11, 12 and 13, 14, 15 are, just as the two pairs of valve connections 3,4 and 5,6, provided in the two planes already referred to above, so that the connection of the different valve connections 3, 4, 5, 6 with the valve chamber 8 can be interrupted, released or partially released by means of the openings 10, 11, 12, 13, 14, 15 by rotating the valve member 1. It is also recognized above all in FIGS. 3.1 to 3.4 and 4.1 to 4.4 that one opening with a larger circumferential extension is provided in each group of openings 10, 11, 12 and 13, 14, 15, namely, the openings 10 and 13, while two openings with a smaller circumferential extension are provided, namely, the openings 11, 12 and 14, 15. The circumferential extensions are selected to be such that when the valve member 1 is brought into one of several main valve positions, which main valve positions can be reached by rotating the valve member by 45° from a preceding main valve position, the openings 11, 12 and 14, 15 provided with a smaller circumferential extension are completely aligned or completely unaligned, and the openings 10 and 13 provided with a longer circumferential extension are aligned with one of the valve connections 3, 4 or 5, 6 in two directly adjacent main valve positions and thus release that valve connection.
The mode of operation for attaining the different main valve positions will be described below. It shall be assumed at first that the opening 10 releases the valve connection 3 in a first main valve position shown in section a) in the far left parts of FIGS. 1 through 4, while the opening 11 releases the valve connection 4. Since the openings 13, 14, 15 have basically the same relative arrangement as the openings 10, 11 and 12, but are rotated in relation to the latter by 45°, none of the openings 13, 14, 15 is aligned in this first main valve position with one of the valve connections 5, 6, so that, as can be recognized in FIG. 2, a flow connection is established only between the valve connection 3 and the valve connection 4 via the valve chamber 8. If the valve member 1 is rotated by 45° starting from the main valve position shown in FIG. 1, namely, in the counterclockwise direction in the view, the opening 10 with the longer circumferential extension continues to be aligned with the valve connection 3, whereas none of the openings 11 and 12 is aligned with the valve connection 4. The opening 15 in the lower group of openings is now aligned with the valve connection 6, whereas the valve connection 5 is not aligned with any of the openings of this group. Thus, there is a connection between the valve connection 3 and the valve connection 6 via the valve chamber 8.
If the valve member 1 is rotated farther by 45° into a third main valve position, the opening 10 with the longer circumferential extension of the upper group of openings is moved out of alignment with the valve connection 3, whereas the opening 12 releases the connection between the valve connection 4 and the valve chamber 8. The opening 13 with the longer circumferential extension in the lower group of openings is now aligned with the valve connection 5, whereas the valve connection 6 is not aligned with any opening. The line connection between the valve connection 4 and the valve connection 5 is then established via the valve chamber 8. If the valve member 1 is rotated farther by 45°, a fourth main valve position is reached. The openings 13 of the lower group of openings continue to be aligned with the valve connection 5 in this position. The valve connection 6 is now aligned with the opening 14, so that the two valve connections 6 and 5 are now in connection with one another via the valve chamber 8. None of the openings of the lower group is now aligned with one of the valve connections 3 or 4, so that the state recognizable in the far right-hand part of FIG. 2 has been reached.
If the valve member 1 were rotated farther by another 45° starting from this fourth main value position shown in section d) in the far right-hand parts of FIGS. 1.1 through 4.4, a state that corresponds to the first main valve position would again be reached because of the exiting symmetry, but the valve member 1 would now have been rotated by 180° in relation to the first main valve position.
The above description shows that the presetting of four main valve positions is essentially also due to the fact that the different groups of openings and the particular circumferential distance or the circumferential extension of these openings are provided in a defined manner. It is self-explanatory that there are intermediate valve positions between these four main valve positions, in which the different openings 10, 11, 12, 13, 14, 15 are not completely aligned with the respective valve connections or are not aligned, but there is only a partial alignment, so that additional flow paths are released, while other flow paths are throttled by reducing the flow cross section. If, for example, an intermediate valve position located between the main valve positions 1 and 2 is reached, the valve connections 3 and 4 are still in connection, but the opening 11 is aligned only partially or by half with the valve connection 4. However, the opening 15 is now partially aligned at the same time with the valve connection 6, so that there is a connection between the valve connections 3, 4 and 6 via the valve chamber 8 in this intermediate state. If an intermediate valve position located between the second and third main valve positions is reached, a connection is now established between the valve connections 3 and 4, on the one hand, and the valve chamber 8, on the other hand, via the openings 10 and 12, whereas the valve connections 5 and 6 are also in connection with the valve chamber 8 via the openings 13 and 15. Thus, a state emerges in which all of the valve connections 3, 4, 5, 6 communicate with one another via the valve chamber 8. If the valve member is brought into an intermediate position between the main valve positions 3 and 4, the valve connection 3 continues to be closed, while the valve connection 6 is now additionally connected via the opening 14 and the valve connections 4, 5 and 6 are thus in connection with one another via the valve chamber 8.
It is recognized from this that when a particular intermediate valve position is assumed, the valve connections now released for the fluid communication are formed by the sum of the valve connections released in the main valve positions located on both sides of the intermediate valve position. By approaching the valve member 1 to one of the main valve positions or by moving it away from the other of the main valve positions, it can be achieved that the valve connections that are released, in principle, in one valve position are released with a larger cross section, while the valve connections released in the main valve position that is located farther away will be throttled more strongly. A defined flow guiding can thus be achieved by generating throttling effects in a defined manner even when more than two valve connections are released.
However, it is of significance that no valve position can be assumed in which at least two of the valve connections do not communicate with one another in order to thus allow a defined fluid flow via this multiway valve.
This type of multiway valve is used, in particular, in vehicle heating/cooling systems in which the coolant circulation of the drive assembly, generally an internal combustion engine, is to be guided, as desired, such that, e.g., the cooling medium circulates only through the drive assembly during a cold start phase and cannot come into contact with any heat exchanger arrangement; that it can circulate between the drive assembly and a heat exchanger arrangement, e.g., a cooler, at a comparatively high cooling medium temperature; that an additional heat exchanger arrangement, e.g., a heating heat exchanger, can be connected into the fluid circulation as an alternative or in addition to the connection of the cooler at a comparatively high cooling medium temperature and when heating is needed in the vehicle, or that a fluid circulation is established between the drive assembly and the heating heat exchanger during the start phase, i.e., in case of a comparatively cold cooling medium and when heating is needed in the vehicle, while the cooler is uncoupled from this circulation.
A problem may arise in such a valve when it develops a defect in one of its valve positions and cannot be adjusted any longer. Particularly critical in this connection is the state in which the multiway valve is connected such that a circulation takes place only through the drive assembly in order to bring the cooling medium or the drive assembly to the desired operating temperature as quickly as possible. If the valve cannot be switched over after the end this start phase, there is a risk for overheating of the cooling medium and the drive assembly.